1. Field of the Invention
This invention relates generally to tube fasteners and methods for controlling the torque applied thereto. More particularly, the present invention provides a method and apparatus for ensuring a predetermined level of torque is achieved and not exceeded during installation of a tube nut on a brake tube having a flared end.
2. Disclosure Information
The principal function of a tube nut is to provide a compressive force to retain an end of a tube in a sealed relationship with an adjacent component. Commonly, this is done using a flared end on the tube and a similarly chamfered flared end receiver on the inside of the component. It has been recognized, however, that fluid may seep from this assembly if there is not enough or too much compressive force generated by the tube nut. Specifically, too little force and the surfaces may not seal and too much force can cause the flared end to crack, providing a passage for fluid seepage.
One solution for this would be to use complex, electronically controlled torque wrenches for applying a torque that is within the acceptable range for proper sealing. However, if the calibration of the electronically controlled wrench drifts, or the wrench malfunctions in some other way, the tube nut may not properly seal the tubular member. Additionally, there is no way for the operator to visually inspect the tube nut to determine whether it will leak, since fluid may not be present when the tube nut is installed.
It would be desirable to have a tube nut torque limiting method and apparatus for installing a tubular member in an internally threaded component that would ensure proper compressive forces for sealing the tubular member. It would be further desirable if the tubular nut could be visually inspected for proper installation.